1. Field
This application generally relates to power production and waste processing. More specifically, it relates to systems and methods for extracting heat energy from compostable material and converting this energy to electricity with the aid of an updraft tower.
2. Prior Art
One of the major problems facing the United States, indeed the world, is that of landfill pollution and inefficient waste processing. Every year the United States alone produces hundreds of millions of tons of municipal solid waste. Much of this waste is not recycled or composted. Of the portion that is composted, the heat energy generated by the composting process is not utilized. Additionally, locating potential landfill sites poses a significant problem as well. Landfills may contaminate ground water or cause other undesired environmental and aesthetic hazards.
Moreover, a chief concern facing the planet is finding alternative, renewable energy sources to replace conventional power plants that burn fossil fuels. Fossil fuel burning power plants, such as coal or oil burning plants, produce a host of unwanted greenhouses gases, which are believed to be a major contributor of global warming.
U.S. Pat. No. 4,275,309, the contents of which are incorporated herein by reference, describes a system for converting solar heat into electrical energy. The system has a collector region where large volumes of air are heated by the sun. This heated air then flows at a high speed towards the center of the structure due to a large pressure differential caused by a tall chimney-like tower that extends upward from the base of the structure. The high speed air drives a turbine that generates electricity. In the art, such systems are also known as a solar updraft towers. However, solar updraft towers in the prior art heat the air in their collector region with only solar energy.
Composting is the purposeful biodegradation of organic matter, such as yard and food waste, performed by micro-organisms, such as bacteria, yeasts and fungi. The microorganisms consume the organic, carbon containing matter and break it down into its simplest parts. This produces a fiber-rich, carbon-containing humus with inorganic nutrients like nitrogen, phosphorus and potassium that can be used as fertilizer, potting soil, or for other important agricultural purposes. Through aerobic respiration microorganisms use oxygen and water to break the matter down. This process generates heat. Temperatures within compost piles can rise as high as 100 to 150 degrees Fahrenheit. Many commercial composting facilities do not harvest or otherwise use the ample heat energy released during the composting process, and allow it to dissipate into the surrounding environment.
Existing composting systems that do utilize the heat energy released from the composting process do not produce electricity. One such system described in the publication BioCycle August 2006, Vol. 47, No. 8, p. 38, uses Isobar super-thermal conductor heat pipes to condense heated water vapor from the compost pile. The condensed vapor is then transferred along the pipes, providing energy to heat water in a large, insulated tank. The heated water can then provide radiant heat to a nearby structure, for example, a floorboard. However, such a system merely transfers the heat produced by the compost pile to provide heat to an adjacent structure. It does not provide a means to generate electricity from the heat energy released by the compost pile; electricity that can be used anywhere, in a myriad of ways.
It is an object of the present application to disclose a system and method that utilizes the heat energy released during the composting process to produce electricity using an updraft tower. It is also another object of the present application to disclose a system and method that utilizes the heat energy released during the composting process to supplement the solar heat energy generated within the collector region of a solar updraft tower to increase output power of the entire system. It is also an object of the present application to disclose a system and method that accomplishes these tasks while reducing landfill pollution by converting compostable waste into a valuable and useful end product (humus) that can be used in agriculture. It is also an object of the present application to disclose an alternative and renewable energy source that produces electricity in a clean, bio-friendly manner, and conserves the Earth's natural resources.
Additional objects, advantages and novel features will be set forth in the description which follows.